Class 1, Div. 2
Where ignitable concentrations of flammable gases, vapors, or liquids are not likely to exist under normal operating conditions.
Class 2, Div. 1
Where ignitable concentrations of combustible dusts can exist all of the time or some of the time under normal operation conditions.
Class 2, Div. 2
Where ignitable concentrations of combustible dust are not likely to exist under normal operating conditions.
Class 3, Div. 1
Where easily ignitable fibers or materials producing combustible flyings are handled, manufactured or used.
Class 3, Div. 2
Where easily ignitable fibers are stored and handled.